Mana Sapphire

If you look close enough, you can see the pure essence of mana swirling beneath the surface.[1]

Mana Sapphires are soulbound items that, when used, regenerate a portion of the user's mana. They are created by Rank 6 of Conjure Mana Gem. While the spell uses the word 'conjure', mana gems are not considered conjured items in that they do not disappear while logged off.